Introduction

Rules governing how numbers should be expressed in different types of texts can vary wildly from one category to another. Check with your instructor to confirm which system works best for your specific scenario.

Suffixes on Ordinal Numerals

Have you ever seen a number with letters following it? It's an ordinal number. Numbers that do not have these suffixes are called cardinal or arabic numbers).

The suffixes that follow these numbers are -st, -nd, -rd, -th, depending on the number: 1st, 2nd, 3rd, 4th, 5th, 6th, 7th, 8th, 9th, 10th, 11th, 12th, 13th, 14th, 15th, 16th, 17th, 18th, 19th, 20th, 21st, 22nd, 23rd, 24th, 25th, 101st, 102nd, 103rd, 104th, 105th, 477th, etc.

Overarching Principles When Choosing Between Numerals or Spelling Numbers

• Use your number format consistently within the same document.

• Choose whichever option is more easily readable by your readership.

That being said, this page will cover generally accepted methods of expressing numbers in texts.

Rules for Numbers in Academic and Non-Technical Writing

1. Write out numbers that can be stated in one or two words in full:

A minimum of two nurses should be on station at any time.

There are forty-eight hours in two days.

Over four hundred prosthetic devices were received, and they all had defects.

Tomorrow, millions of people will request the new prescription drug from their pharmacists.

I spent four hundred dollars on pizza yesterday.

The satellite's optical lenses cost six thousand dollars.

2. Conversely, use numerals for numbers containing more than two words:

There are over 672 different tracks available on the new synthesizer software.

I spent $432 on pizza yesterday.

The satellite's optical lenses cost $6248.

3. Always write out the number in full if it starts the sentence. Avoid using numbers that require more than two words. For those situations, use words such as about, approximately, exactly, precisely, etc.:

Forty people will require assistance from a sports medical expert with their physical rehabilitation.

About four hundred physics geeks attended the presentation on the nearly quantized conductance plateau of vortex mode in an iron-based superconductors.

4. Fractions should be written out in full, with hyphens:

Nearly one-fourth of all police officers are trained on the use of the expandable baton.

5. Use a numeral before million, billion, trillion, quadrillion for ease of reading:

The politician claimed that the country reached a gross GDMRP of 400 billion.

6. Use numerals for addresses, dates, degrees, divisions in a book, measurements, pages, prices greater than two words, percentages, and times. Use either "$" or "dollars" when expressing prices where that currency is appropriate to use. If you use a large quantity of numbers in a text, do not alternate between one format (spelling out in full) and another format (using just the numerals). Instead, use the same format throughout. In the example below, you can see that the number "3" should normally be spelled out; however, the author uses the numeral instead because of the other numbers in the same sentence.

Page 3 of chapter 10 indicates that 24 units of iodine heated to 36 degrees Celsius will be required to make a soluble mixture at the cost of $4 per day in order to save 98 percent of the population before 3 o'clock (3:00 pm) on Friday.

Quizzes

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